93237 Wearable electrocardiographic rhythm derived monitoring for 24 hours by continuous computerized monitoring and non-continuous recording, and real-time data analysis utilizing a device capable of producing intermittent full-sized waveform tracings, possibly patient activated; physician review and interpretation.
Revised Code ( 01/01/2009 ) The purpose of this study is to evaluate the patient's ambient heart rhythm using wearable electrocardiographic rhythm-derived monitoring. A technician places ECG leads on the patient's chest, and the electrocardiographic signals are monitored for 24 hours. A computer classifies different ECG waveforms in real time. Intermittent full-sized waveform tracings are generated when the computer flags an abnormal rhythm or possibly when the patient activates the device. A report is generated by the computer, often with the help of a technician. If this is done without physician review and interpretation, report 93236. If physician review and interpretation are billed separately, report 93237. If monitoring and data analysis with report are to be billed together with physician review and interpretation, report 93235.

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It appears that if you had medical necessity to bill this code beyond 24 hours there is no limitation.